Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units From Wikipedia, the free encyclopedia Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors. 1 Techniques 1.1 Process 1.2 Multiplication factors 1.3 Table ordering 2 Tables of conversion factors 2.1 Length 2.2 Area 2.3 Volume 2.4 Plane angle 2.5 Solid angle 2.6 Mass 2.7 Density 2.8 Time 2.9 Frequency 2.10 Speed or velocity 2.11 Flow (volume) 2.12 Acceleration 2.13 Force 2.14 Pressure or mechanical stress 2.15 Torque or moment of force 2.16 Energy 2.17 Power or heat flow rate 2.18 Action 2.19 Dynamic viscosity 2.20 Kinematic viscosity 2.21 Electric current 2.22 Electric charge 2.23 Electric dipole 2.24 Electromotive force, electric potential difference 2.25 Electrical resistance 2.26 Capacitance 2.27 Magnetic flux 2.28 Magnetic flux density 2.29 Inductance 2.30 Temperature 2.31 Information entropy 2.32 Luminous intensity 1 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units 2.33 Luminance 2.34 Luminous flux 2.35 Illuminance 2.36 Radiation - source activity 2.37 Radiation - exposure 2.38 Radiation - absorbed dose 2.39 Radiation - equivalent dose 3 Software tools 4 See also 5 Notes and references 6 External links Process The process of conversion depends on the specific situation and the intended purpose. This may be governed by regulation, contract, technical specifications or other published standards. Engineering judgment may include such factors as: The precision and accuracy of measurement and the associated uncertainty of measurement. The statistical confidence interval or tolerance interval of the initial measurement. The number of significant figures of the measurement. The intended use of the measurement including the engineering tolerances. Historical definitions of the units and their derivatives used in old measurements; e.g., international foot vs. US survey foot. Some conversions from one system of units to another need to be exact, without increasing or decreasing the precision of the first measurement. This is sometimes called soft conversion. It does not involve changing the physical configuration of the item being measured. By contrast, a hard conversion or an adaptive conversion may not be exactly equivalent. It changes the measurement to convenient and workable numbers and units in the new system. It sometimes involves a slightly different configuration, or size substitution, of the item. Nominal values are sometimes allowed and used. Multiplication factors Conversion between units in the metric system can be discerned by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10−6 metre). Table ordering Within each table, the units are listed alphabetically, and the SI units (base or derived) are highlighted. 2 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units This article gives lists of conversion factors for each of a number of physical quantities, which are listed in the index. For each physical quantity, a number of different units (some only of historical interest) are shown and expressed in terms of the corresponding SI unit. Legend Symbol Definition ≡ exactly equal ≈ approximately equal to digits indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) (H) of chiefly historical interest Length 3 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units Length Name of unit Symbol Definition Relation to SI units ångström Å ≡ 1 × 10−10 m ≡ 0.1 nm ≡ 149 597 870 700 m ≈ Distance from astronomical unit AU ≡ 149 597 870 700 m [1] Earth to Sun 1 −3 barleycorn (H) = ⁄3 in (see note above about rounding) ≈ 8.46×10 m bohr, atomic unit ≈ a0 = Bohr radius of hydrogen of length 5.291 772 1092(17) × 10−11 m[2] cable length ≡ 608 ft ≈ 185.3184 m (imperial) cable length ≡ 1⁄ nmi ≡ 185.2 m (International) 10 cable length (US) ≡ 720 ft = 219.456 m chain (Gunter's; ch ≡ 66 ft (US) ≡ 4 rods [3] ≈ 20.116 84 m Surveyor's) cubit (H) ≡ Distance from fingers to elbow ≈ 18 in ≈ 0.5 m ell (H) ell ≡ 45 in [4] (In England usually) = 1.143 m fathom ftm ≡ 6 ft [4] = 1.8288 m fermi fm ≡ 1 × 10−15 m[4] ≡ 1 × 10−15 m 7 finger ≡ ⁄8 in = 0.022 225 m 1 finger (cloth) ≡ 4 ⁄2 in = 0.1143 m foot (Benoît) (H) ft (Ben) ≈ 0.304 799 735 m Legally defined as 1.033 English feet in foot (Cape) (H) ≈ 0.314 858 m 1859 foot (Clarke's) (H) ft (Cla) ≈ 0.304 797 2654 m foot (Indian) (H) ft Ind ≈ 0.304 799 514 m 1 foot, metric mf ≡ √ ⁄10 m ≈ 0.31622776601 m 1 foot, metric (long) lmf ≡ ⁄3 m ≈ 0.3 m foot, metric (short) smf ≡ 0.30 m ≡ 0.30 m 1 foot (International) ft ≡ 0.3048 m ≡ ⁄3 yd ≡ 12 inches ≡ 0.3048 m foot (Sear's) (H) ft (Sear) ≈ 0.304 799 47 m 1200 [5] foot (US Survey) ft (US) ≡ ⁄3937 m ≈ 0.304 800 610 m 1 −3 french; charriere F ≡ ⁄3 mm = 0.3×10 m furlong fur ≡ 10 chains = 660 ft = 220 yd [4] = 201.168 m 4 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units hand ≡ 4 in [4] ≡ 0.1016 m 1 1 inch (International) in ≡ 2.54 cm ≡ ⁄36 yd ≡ ⁄12 ft ≡ 0.0254 m ≈ 1 hour walk, Currently defined in US league (land) lea as 3 Statute miles,[3] but historically ≈ 4828 m varied from 2 to 9 km light-day ≡ 24 light-hours ≡ 2.590 206 837 12 × 1013 m light-hour ≡ 60 light-minutes ≡ 1.079 252 8488 × 1012 m light-minute ≡ 60 light-seconds ≡ 1.798 754 748 × 1010 m ≡ Distance light travels in one second in light-second ≡ 299 792 458 m vacuum ≡ Distance light travels in vacuum in light-year ly = 9.460 730 472 5808 × 1015 m 365.25 days [6] 1 [7] line ln ≡ ⁄12 in = 0.002 116 m link (Gunter's; lnk ≡ 1⁄ ch [4] ≡ 0.66 ft (US) ≡ 7.92 in ≈ 0.201 1684 m Surveyor's) 100 link (Ramsden's; lnk ≡ 1 ft [4] = 0.3048 m Engineer's) 1 ≡ Distance light travels in ⁄299 792 458 of metre (SI base a second in vacuum.[8] unit) m ≡ 1 m 1 (meter) ≈ ⁄10 000 000 of the distance from equator to pole. 1 −4 mickey ≡ ⁄200 in = 1.27 × 10 m micrometre (old: µ ≡ 1 × 10−6 m micron) mil; thou mil ≡ 1 × 10−3 in ≡ 2.54 × 10−5 m mil (Sweden and mil ≡ 10 km = 10 000 m Norway) mile (geographical) ≡ 6082 ft = 1 853.7936 m (H) mile (international) mi ≡ 80 chains ≡ 5280 ft ≡ 1760 yd ≡ 1 609.344 m mile (tactical or ≡ 6000 ft ≡ 1 828.8 m data) mile (telegraph) mi ≡ 6087 ft = 1 855.3176 m (H) ≡ 5280 US Survey feet ≡ (5280 × mile (US Survey) mi 1200 ≈ 1 609.347 219 m ⁄3937) m 1 [4] nail (cloth) ≡ 2 ⁄4 in = 0.057 15 m 5 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units nanometre nm ≡ 1 × 10−9 m ≡ 1 × 10−9 m nautical league NL; nl ≡ 3 nmi [4] = 5556 m nautical mile NM (Adm); = 6080 ft = 1 853.184 m (Admiralty) nmi (Adm) nautical mile NM; nmi ≡ 1852 m[9] ≡ 1852 m (international) nautical mile (US ≡ 1853.248 m ≡ 1853.248 m pre 1954) pace ≡ 2.5 ft [4] = 0.762 m palm ≡ 3 in [4] = 0.0762 m Distance of star with parallax shift of parsec pc one arc second from a base of one ≈ 3.085 677 581 × 1016 m[10] astronomical unit pica ≡ 12 points Dependent on point measures. point (American, pt ≡ 1⁄ in ≈ 0.000 351 450 m English)[11][12] 72.272 1 1 ≡ ⁄12 × ⁄72 of pied du roi; ≈ 0.000 375 97 m; point (Didot; pt European) [12][13] After 1878: After 1878: 5 ≡ ⁄133 cm ≈ 0.000 375 939 85 m point (PostScript) 1 [11] pt ≡ ⁄72 in = 0.000 3527 m [11] 1 point (TeX) pt ≡ ⁄72.27 in = 0.000 351 4598 m 1 quarter ≡ ⁄4 yd = 0.2286 m rod; pole; perch rd ≡ 161⁄ ft = 5.0292 m (H) 2 rope (H) rope ≡ 20 ft [4] = 6.096 m shaku (Japan) ≡ 10/33 m ≈ 0.303 0303 m span (H) ≡ 9 in [4] = 0.2286 m spat [14] ≡ 1 × 1012 m stick (H) ≡ 2 in = 0.0508 m picometre (old: pm ≡ 1 × 10−12 m bicron, stigma) 1 −5 twip twp ≡ ⁄1440 in = 1.7638×10 m x unit; siegbahn xu ≈ 1.0021 × 10−13 m [4] yard (International) yd ≡ 0.9144 m [5] ≡ 3 ft ≡ 36 in ≡ 0.9144 m 6 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units Area 7 of 38 1/3/2017 9:48 AM Conversion of units - Wikipedia https://en.wikipedia.org/wiki/Conversion_of_units Area Name of unit Symbol Definition Relation to SI units acre (international) ac ≡ 1 ch × 10 ch = 4840 sq yd ≡ 4 046.856 4224 m2 ≡ 10 sq ch = 4840 sq yd, also acre (US survey) ac ≈ 4 046.873 m2[15] 43 560 sq ft are a ≡ 100 m2 = 100 m2 barn b ≡ 10−28 m2 = 10−28 m2 barony ≡ 4000 ac ≈ 1.618 742 × 107 m2 board bd ≡ 1 in × 1 ft = 7.741 92 × 10−3 m2 boiler horsepower equivalent bhp ≡ 1 ft2 × 1 bhp / (240 BTU /h) ≈ 12.958 174 m2 direct radiation EDR IT π −4 2 circular inch circ in ≡ ⁄4 sq in ≈ 5.067 075 × 10 m π 2 −10 2 circular mil; circular thou circ mil ≡ ⁄4 mil ≈ 5.067 075 × 10 m cord ≡ 192 bd = 1.486 448 64 m2 cuerda (PR Survey) cda ≡ 1 cda x 1 cda = 0.971 222 acre ≡ 3 930.395 625 m2 dunam ≡ 1000 m2 = 1000 m2 guntha (India) ≡ 121 sq yd ≈ 101.17 m2 hectare ha ≡ 10 000 m2 ≡ 10 000 m2 hide ≈ 120 ac (variable) ≈ 5 × 105 m2 1 2 rood ro ≡ ⁄4 ac = 1 011.714 1056 m section ≡ 1 mi × 1 mi = 2.589 988 110 336 × 106 m2 shed ≡ 10−52 m2 = 10−52 m2 square (roofing) ≡ 10 ft × 10 ft = 9.290 304 m2 1 2 square chain (international) sq ch ≡ 66 ft × 66 ft = ⁄10 ac ≡ 404.685 642 24 m ≡ 66 ft (US) × 66 ft (US) = 1⁄ US square chain (US Survey) sq ch 10 ≈ 404.6873 m2 survey acre square foot sq ft ≡ 1 ft × 1 ft ≡ 9.290 304 × 10−2 m2 ≈ square foot (US Survey) sq ft ≡ 1 ft (US) × 1 ft (US) 9.290 341 161 3275 × 10−2 m2